JP2010025606A - Bent pipe stress evaluation method and bent pipe stress evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bent pipe stress evaluation method and a bent pipe stress evaluation device capable of evaluating axial and circumferential stress generated in the bent pipe precisely from the amount of sectional flatness in a straight pipe connected to the bent pipe even if it is not possible to directly measure the bent pipe section since other buried objects, or the like approach. <P>SOLUTION: A control section 7 sets appropriate amount-of-flatness measurement section 41 according to pipelines to an exposed straight pipe 35a, based on previously input pipeline information. The amount-of-flatness measurement section 41 is set at a position separated by measurement distance 47 that is 0.5 to 1.5 times larger than a pipe diameter 45 in the direction of the straight pipe 35a from a pipe connection section 43, namely a connection section of a bent pipe 37 and the straight pipe 35a. Then, the amount of flatness in the straight pipe is calculated from the amount of flatness in the straight pipe 35a at the amount-of-flatness measurement section 41. Then, the amount of flatness in the bent pipe is calculated from a flatness ratio at the position of the amount-of-flatness measurement section 41 and the measured amount of flatness in the straight pipe, thus calculating axial and circumferential stress generated in the bent pipe. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bending pipe stress evaluation method and a bending pipe stress evaluation apparatus capable of evaluating stress generated in a bending pipe in a pipe line in which a straight pipe and a bending pipe are connected.

  Conventionally, if the buried pipe is affected by ground subsidence and stress occurs in the buried pipe, the sediment on the pipe is removed as appropriate so that the stress does not exceed a certain value, Stress relieving work is performed to reduce this. Therefore, stress evaluation of the pipeline is important.

  On the other hand, the pipe line is formed by combining a straight pipe and a curved pipe in order to avoid an obstacle or to perform the construction conditions of the burial work. As described above, when the buried pipe is affected by the ground subsidence, the stress generated in the pipe is usually the maximum stress in the central portion of the curved pipe. Therefore, stress evaluation at the central part of the curved pipe is particularly important.

  FIG. 8 is a diagram illustrating a stress evaluation method for the curved pipe 75 in the pipe line embedded in the ground 71. A curved pipe 75 is connected between the straight pipe 73a and the straight pipe 73b. As described above, when the pipe line is affected by ground subsidence or the like, the maximum stress is often generated particularly in the central portion of the curved pipe 75 (in the vicinity of the arrow X portion in the figure).

  In order to know the stress of the curved pipe 75, the ground 71 is excavated as shown in FIG. Thereafter, by directly measuring the stress of the exposed bent tube 75, the stress of the bent tube 75 can be accurately known.

  As such a stress evaluation method for a curved pipe, for example, the distribution of the principal stress difference is measured while moving the magnetic anisotropy sensor in the circumferential direction of the curved pipe, and the value is returned to the Kalman equation. There is a method for estimating the stress generated in a curved pipe (Patent Document 1).

  In addition, there is a method of measuring a flat amount in a central section of a bent pipe portion and calculating a stress generated in the bent pipe portion from the flat amount by stress calculation (Patent Document 2).

  In addition, a bent pipe part is provided in the concealed part, and the straight pipe part connected to the bent pipe part is exposed, and the stress or strain of the bent pipe part is estimated by measuring the stress of the straight pipe part with a magnetostrictive device. There is a method (Patent Document 3).

JP 2003-177066 A Japanese Patent Laid-Open No. 2003-344184 JP-A-5-281062

  However, with the technique described in Patent Document 1, it is possible to measure the stress generated in the curved pipe with extremely high accuracy. However, when there is another embedded object around the curved pipe, When it is difficult to access the curved pipe, such as when it is provided in a wall, there is a problem that the stress of the curved pipe cannot be directly measured.

  In addition, in the technique described in Patent Document 2, it is a principle that the flattening amount of the curved pipe at the initial stage at the time of construction of the curved pipe is known, but usually the flattening amount of the initial section of the curved pipe is unknown. Since there are many cases, there is a problem that the stress of the bent pipe cannot be accurately known. Moreover, since it is necessary to measure the flat amount of a curved pipe directly like patent document 1, when there exists another buried object around a curved pipe, a curved pipe is provided in the wall of a structure, etc. In some cases, such as when it is difficult to access the curved pipe, there is a problem that the stress of the curved pipe cannot be directly measured.

  In addition, the technique described in Patent Document 3 obtains the relationship between the circumferential stress / strain generated in the straight pipe portion by experiments and the stress generated in the curved pipe to be diagnosed in advance, and is directly corrected by a magnetostrictive device in the field. The stress in the curved pipe part is diagnosed by obtaining the circumferential stress of the pipe part and comparing it with the experimental value.

  However, although there is a description that the stress of the curved pipe part is affected by the deformation of the straight pipe part, the influence of the deformation is approximated by sin2θ that approximates the deviation at each angle between the output of the magnetostrictive device and the approximate value of sinθ. There is a problem that the degree of deviation from the actual stress is not clear when considered in this way. That is, since the stress in the axial direction in the straight pipe portion that is affected by the cross-sectional flatness of the curved pipe cannot be obtained with high accuracy, the axial and circumferential stresses generated in the curved pipe as a result are estimated with high accuracy. There is a problem that you can't.

  The present invention has been made in view of such a problem, and even when other embedded objects are close to each other and the curved pipe portion cannot be directly measured, the straight pipe connected to the curved pipe is used. It is an object of the present invention to provide a curved pipe stress evaluation method and a curved pipe stress evaluation apparatus capable of accurately evaluating axial and circumferential stresses generated in a curved pipe from the cross-sectional flat amount.

  In order to achieve the above-mentioned object, the first invention is a stress evaluation method of a curved pipe in a pipe body in which a straight pipe and a curved pipe are connected, and the first pipe and the curved pipe are connected to each other from the connecting portion. A step (a) of setting a flat amount measuring unit at a position 0.5 to 1.5 times the diameter of the straight pipe on the straight pipe side, and a step of measuring the flat amount of the straight pipe by the flat amount measuring unit ( b), a step (c) of calculating the flat amount of the curved pipe based on the flat amount of the straight pipe, and a step (d) of calculating a stress of the curved pipe based on the flat amount of the curved pipe. A stress evaluation method for a curved pipe, comprising:

  According to the pipe coefficient of the tubular body, a flatness ratio between a flattening amount in the central cross section of the curved pipe and a flattening amount of the straight pipe in the flattening amount measuring unit is calculated in advance, and in the step (c), the flattening The flat amount of the bent pipe may be calculated from the ratio.

  According to 1st invention, the flat amount of a straight pipe is measured in the position 0.5 to 1.5 times the diameter of a straight pipe from the connection part with a curved pipe to the straight pipe side, From the flat amount of a straight pipe, Since the flattening amount of the bent pipe and the stress due thereto are calculated, the stress of the bent pipe can be accurately evaluated even when the flattened amount of the bent pipe at the time of construction is unknown. In particular, by calculating the ratio of the flat tube flat amount and the flat tube center flat amount at each measurement position for each pipe coefficient, the stress of the bent tube can be calculated easily and accurately from the flat tube flat amount. be able to.

  A second invention is a stress evaluation apparatus for a curved pipe in a pipe body in which a straight pipe and a curved pipe are connected, and the straight pipe is connected to the straight pipe side from a connecting portion between the straight pipe and the curved pipe. Based on the means for setting the flat amount measuring unit at a position 0.5 to 1.5 times the diameter, the means for measuring the flat amount of the straight pipe in the flat amount measuring unit, and the flat amount of the straight pipe A bending pipe stress evaluation apparatus comprising: means for calculating a flattening amount of the bent pipe; and means for calculating a stress of the bent pipe based on the flattening amount of the bent pipe.

  According to the second aspect of the present invention, the straight pipe flatness measuring unit is set at a position 0.5 to 1.5 times the diameter of the straight pipe from the connecting part to the curved pipe to the straight pipe side. Since the flattened amount of the bent pipe and the stress due to this are calculated from the amount, even if the flattened amount of the bent pipe at the time of construction is unknown, the stress of the bent pipe can be accurately evaluated.

  According to the present invention, even when other embedded objects are close to each other and the curved pipe portion cannot be directly measured, it is possible to accurately convert the curved pipe from the cross-sectional flat amount of the straight pipe connected to the curved pipe. It is possible to provide a bent pipe stress evaluation method and a bent pipe stress evaluation apparatus capable of evaluating the generated axial and circumferential stresses.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a hardware configuration diagram for realizing a stress evaluation apparatus 1 for a curved pipe according to the present embodiment. The bent pipe stress evaluation device 1 is mainly composed of an analysis device 3 and a flatness measuring device 5. The analysis device 3 is a computer, and the flatness measuring device 5 only needs to be able to measure the outer shape of the tubular body. For example, a digital caliper can be used.

  The analysis device 3 includes a control unit 7, a storage unit 9, a media input / output unit 11, a communication control unit 13, an input unit 15, a display unit 17, a peripheral device I / F unit 19, and the like. Connected.

The control unit 7 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.
The CPU calls a program stored in the storage unit 9, ROM, recording medium, etc. to a work memory area on the RAM, executes it, controls the drive of each device connected via the bus 21, and evaluates the stress of the curved pipe. The processing performed by the device 1 is realized.

The ROM is a non-volatile memory and permanently holds a computer boot program, a program such as BIOS, data, and the like.
The RAM is a volatile memory, and temporarily stores programs, data, and the like loaded from the storage unit 9, ROM, recording medium, and the like, and includes a work area used by the control unit 7 for performing various processes.

The storage unit 9 is an HDD (hard disk drive), and stores a program executed by the control unit 7, data necessary for program execution, an OS (operating system), and the like. As for the program, a control program corresponding to an OS (operating system) and an application program corresponding to processing described later are stored.
Each of these program codes is read by the control unit 7 as necessary, transferred to the RAM, read by the CPU, and executed as various means.

  The media input / output unit 11 (drive device) performs data input / output. For example, a floppy (registered trademark) disk drive, CD drive (-ROM, -R, RW, etc.), DVD drive (-ROM, -R, etc.) -RW etc.) and media input / output devices such as MO drives.

  The communication control unit 13 includes a communication control device, a communication port, and the like, and is a communication interface that mediates communication between a computer and a network, and performs communication control between other computers via the network.

The input unit 15 inputs data and includes, for example, a keyboard, a pointing device such as a mouse, and an input device such as a numeric keypad.
An operation instruction, an operation instruction, data input, and the like can be performed on the computer via the input unit 15.

  The display unit 17 includes a display device such as a CRT monitor and a liquid crystal panel, and a logic circuit (such as a video adapter) for realizing the video function of the computer in cooperation with the display device.

  The peripheral device I / F (interface) unit 19 is a port for connecting a peripheral device to the computer, and the computer transmits and receives data to and from the peripheral device via the peripheral device I / F unit 19. The peripheral device I / F unit 19 is configured by USB, IEEE 1394, RS-232C, or the like, and usually includes a plurality of peripheral devices I / F.

  The flatness measuring device 5 is connected to the peripheral device I / F unit 19. Measurement data from the flatness measuring device 5 is input from the peripheral device I / F unit 19 to the analysis device 3 and stored in the storage unit 9 or the like. The connection form between the peripheral device I / F unit 19 and the flatness measuring device 5 may be wired or wireless.

  The bus 21 is a path that mediates transmission / reception of control signals, data signals, and the like between the devices.

  Next, the operation of the bent pipe stress evaluation apparatus 1 will be described. FIG. 2 is a flowchart showing a process of evaluating the stress of the curved pipe by the stress evaluation apparatus 1 for the curved pipe.

  First, the control unit 7 sets a straight tube flat amount measuring unit that measures a flat tube flat amount based on information on a tube diameter that is a measurement target stored in the storage unit 9 in advance (step 101).

  In setting the flatness measuring unit, first, the ground is excavated to expose the pipeline. FIG. 3 and FIG. 4 are diagrams showing pipes to which the straight pipes 35a and 35b and the curved pipe 37 are respectively connected. As shown in FIG. 3, the curved pipe 37 is connected to the straight pipes 35 a and 35 b and is embedded in the ground 34. In the vicinity of the curved pipe 37, another buried pipe 39 is buried. As described above, if the stress can be directly measured in the vicinity of the central portion (arrow A in the figure) of the curved pipe 37, the stress in the axial direction and the circumferential direction of the curved pipe can be accurately known by a conventional method. However, since the buried pipe 39 exists in the vicinity of the curved pipe 37, the stress of the curved pipe 37 cannot be directly measured.

  FIG. 4 is a diagram illustrating a state where the ground 34 is excavated so that the straight pipes 35a and 35b are exposed. If there is no buried pipe 39, the ground 34 may be excavated so that the curved pipe 37 is exposed. However, if the stress measurement of the curved pipe 37 is impossible, the axis of the curved pipe is determined from the flat amount of the straight pipe 35a. Evaluate direction and circumferential stresses.

  The control unit 7 sets an appropriate flat amount measuring unit 41 corresponding to the pipeline in the exposed straight pipe 35a based on the pipeline information input in advance and held in the storage unit 9. The flat amount measuring unit 41 has a measuring unit distance 47 that is 0.5 to 1.5 times the pipe diameter 45 in the direction of the straight pipe 35a from the pipe connecting part 43 that is a connecting part of the curved pipe 37 and the straight pipe 35a. Set to a distant position.

  Here, when the measurement part distance 47 is made smaller than 0.5 and the flatness measurement part 41 is set on the curved pipe 37 side, the measured value is a change in the outer diameter due to welding between the curved pipe 37 and the straight pipe 35a. It is difficult to accurately measure the amount of flatness associated with the stress acting on the curved pipe 37 because it is affected by the influence and the change in the amount of flatness due to the thickened joint. Therefore, the stress in the axial direction and the circumferential direction of the curved pipe 37 cannot be accurately evaluated.

  On the other hand, when the measuring portion distance 47 is set to be larger than 1.5 and the flat amount measuring portion 41 is set at a position far from the curved pipe 37 from the pipe connecting portion 43, the flatness of the straight pipe 35a due to the stress generated in the curved pipe 37 Since the amount becomes too small, the stress in the curved pipe 37 cannot be accurately evaluated. Therefore, it is desirable to set the measurement unit distance 47 between 0.5 times and 1.5 times the pipe diameter 45 from the pipe connection part 43 between the curved pipe 37 and the straight pipe 35a to the straight pipe 35a side. As close as possible to the pipe connecting portion 43 within the range where the bent pipe 37 and the straight pipe 35a are not affected, it is desirable that the accuracy is high.

  Next, the control unit 7 measures the flat amount of the straight pipe 35a in the flat amount measuring unit 41 by the flat amount measuring device 5 (step 102). The flat amount is measured by, for example, digital calipers. The flat amount is measured, for example, by measuring the outer diameter of the straight pipe in two directions perpendicular to each other, and calculating from the flat amount from the initial stage of construction in each measurement direction.

  FIG. 5 is a diagram showing a method for measuring the flatness. When measuring the flattening amount of the tube body 49, as shown in FIG. 5A, the direction connecting the tube top 51 and the tube bottom 52 in the cross section 50 at the measurement site of the tube body 49 (the direction of arrow C in the figure). And the outer diameter in the direction perpendicular to this (the direction of arrow B in the figure). The pipe top 51 is an extension line of the outermost periphery of the bending in the curved pipe part, and the pipe bottom 52 is an extension line of the innermost periphery of the bending in the curved pipe part. Therefore, the arrow C direction in FIG. 5A is the bending direction of the curved pipe connected to the straight pipe, and the arrow B is the direction perpendicular to the arrow C.

  FIG. 5B is a diagram illustrating a flat state of the cross section 50. The cross section 50a is the cross section 50 of the tubular body in the initial installation state, and the outer diameters in each direction (arrow B direction and C direction in the figure) of the cross section 50a are d01 and d02, respectively. That is, d01 and d02 match if the tube is a perfect circle when installed.

  Even a straight pipe may be slightly flattened during manufacture. However, since the flattening amount of the straight pipe often remains recorded, d01 and d02 can be accurately obtained from the flattening amount data at the time of installation. Even if the initial flat amount of the straight pipe is unknown, the flat amount at the time of manufacturing the straight pipe is extremely small compared to the curved pipe, so high reliability even if the initial flat amount of the straight pipe is zero. Can be secured.

The cross section 50b is a cross section 50 in a state in which the curved pipe is flattened due to the stress generated in the curved pipe, and the straight pipe connected to the curved pipe is flattened due to the flat deformation of the curved pipe. In the cross section 50b in a state where the tube body is flat, the outer shapes in the arrow B direction and the C direction in the drawing are d1 and d2, respectively. At this time, as shown in FIG. 5B, the amount of displacement on both sides of the tubular body when the outer shape of d01 is deformed to d1 is denoted by ei1. Similarly, let ei2 be the amount of displacement on both sides of the tubular body when the outer shape of d02 is deformed to d2. Then, the in-plane bending flat amount e1 is calculated by the equation (1).
e1 = 2 (ei1 + ei2) (1)

  Next, the control unit 7 inputs the outer diameter of the straight pipe 35a measured in step 102 to the analyzer 3 (step 103). For example, the measured outer diameter data is taken into the analysis device 3 and stored in the storage unit 9. Data input may be performed by the peripheral device I / F unit 19 storing data from the flatness measuring device 5 in the storage unit 9 or via the input unit 15. Further, the media input / output unit 11 may be used. In addition, data may be transmitted from another computer via a network. The control unit 7 calculates the flat amount e1 from the input outside diameter data of the straight pipe 35a using the equation (1), and stores the flat amount data in the storage unit 9.

  Next, the control unit 7 determines the ratio of the flat amount of the straight pipe 35a and the flat amount of the curved pipe 37, which is stored in advance in the storage unit 9, based on the straight pipe 35a flat amount data captured in step 103. The flattening amount of the curved pipe 37 is calculated from the data (step 104).

  Here, in the state where the curved pipe and the straight pipe are connected, when a stress is generated in the curved pipe, the cross section of the straight pipe connected to the curved pipe is affected by the flatness of the cross section of the curved pipe, Although it is small compared to a curved pipe, it flattens greatly. The size of the flatness ratio, which is the ratio between the flattening amount of the straight pipe and the flattening amount of the curved pipe, is a substantially constant ratio determined by the distance from the curved pipe. This is the same ratio even if a moment proportional to the distance from the load point is applied (model) or a constant moment is applied regardless of the distance (model). .

Therefore, in a state where the curved pipe and the straight pipe are connected in advance by experiments and calculations, a load is applied to one end of the straight pipe, and the flat amount of the curved pipe portion accompanying the load in this case, the straight pipe and the curved pipe By calculating the ratio of the straight pipe flatness at a predetermined distance (for example, 0.5 times the pipe diameter) from the connecting part to the straight pipe direction, it is easy to bend from the flat pipe flatness. You can know the flatness of the tube. The flatness ratio varies depending on the pipe coefficient (coefficient represented by tR / r ² when the radius of the pipe is r, the radius of curvature of the curved pipe is R, and the thickness is t). It is necessary to obtain the aspect ratio.

  Next, the control unit 7 calculates the axial stress generated in the curved pipe 37 based on the flat amount of the curved pipe 37 calculated in step 104 (step 105). In calculating the stress of the curved pipe 37, the moment can be obtained from the flat amount generated in the curved pipe 37, and the axial and circumferential stresses generated in the curved pipe 37 can be calculated from the moment. As a method for calculating the stress in the axial direction and the circumferential direction from the flat amount of the curved pipe 37, for example, a method described in Japanese Patent Application Laid-Open No. 2003-344184 can be used.

  Next, the control unit 7 outputs the stress in the axial direction and the circumferential direction of the curved pipe 37 calculated in Step 105 by a predetermined method. The output of the calculation data may be displayed on the display device via the display unit 17. Moreover, you may output to the file by a suitable file format. In addition, data may be transmitted to another computer via a network. As described above, the stress in the axial direction and the circumferential direction of the curved pipe 37 can be known.

  The validity of the axial and circumferential stresses of the curved pipe calculated by the curved pipe stress evaluation apparatus 1 according to the present invention was verified. FIG. 6 is a schematic diagram showing a pipeline model used in the experiment.

  A curved pipe 55 wound at an opening angle of 90 ° was connected between the straight pipe 53a and the straight pipe 53b for use in the experiment. The straight pipes 53a and 53b were steel pipes having an outer diameter of 318.5 mm and a thickness of 9.9 mm. The curved pipe 55 was a steel pipe having an outer diameter of 318.5 mm, a thickness of 11.8 mm, and a curvature radius of 457.2 mm. The pipe connecting portion 57 is a joint portion between the straight pipe 53 a and the curved pipe 55. The straight pipes 53a and 53b and the curved pipe 55 were joined by welding.

  Flange 63a, 63b is provided in the edge part on the opposite side to the pipe connection part 57 which is a junction part with the curved pipe 55 of each of the straight pipes 53a, 53b, and the straight pipe 53b is connected with respect to the floor 65 by the flange 63b. And fixed vertically.

  A load in the direction of arrow W was applied to the end portion (flange 63a) of the straight pipe 53a with a jack (not shown), and the flatness of each of the straight pipe 53a and the curved pipe 55 was measured. Note that an arrow W is a direction perpendicular to the straight pipe 53a and the curved pipe 55 is bent.

  The flatness measurement unit 67 of the straight pipe 53a is set at a position away from the pipe connection part 57 by the measurement unit distance 61 (= L) on the straight pipe 53a side. The measurement unit distance 61 was set at a position 0.5 to 1.5 times the tube diameter 59 (= D) (L = 0.5D to 1.5D). In measuring the outer diameter of the straight pipe 53a, digital calipers were used to measure the outer shape in two directions, that is, the bending direction of the bent pipe 55 and the direction perpendicular thereto, corresponding to the B direction and the C direction in FIG. . The flattening amount of the straight pipe was determined from the measured outer diameter data using the equation (1). Further, the flattening amount of the bent pipe 55 was also measured by the same method.

  FIG. 7 shows the flatness measurement result in each flatness measurement unit 67 (measurement unit distance 61). The analysis result 69 is an analysis result obtained by calculating the flat amount at each point in the straight pipe by the analysis by the finite element method from the actually measured value (E point) of the flat amount of the curved pipe. As is clear from FIG. 7, the analysis result and each measured value (F, G, H points) are in good agreement. In addition, E point shows the flat amount in the center part of the bending of the curved pipe 55, F point shows L = 0.5D, G point shows L = 1.0D, H point shows the flat amount in L = 1.5D.

  Table 1 shows a comparison result between an actual measurement value and an analysis value by a finite element method with respect to a flatness ratio obtained by dividing a flat tube flat amount by a flat tube flat amount.

  In Table 1, L indicates the measurement part distance 61 and D indicates the tube diameter 59. The analysis result 1 shows the analysis result in a model in which a moment proportional to the distance from the load point is applied, and the analysis result 2 shows the analysis result in a model in which a constant moment is applied regardless of the distance.

  As is clear from Table 1, the flatness ratio between the straight pipe portion and the curved pipe portion is determined by the measurement position regardless of the analysis model. Therefore, if the pipe coefficients are the same, for example, by measuring the flat amount of the straight pipe at L = 0.5D, the flat amount of the curved pipe is easily about twice the flat amount of the straight pipe. It can be calculated.

  Although omitted in FIG. 7, the measurement result of the flat amount at the position of L <0.5D is affected by the welding of the straight pipe and the curved pipe, and the vicinity of the connection portion is thick. However, an accurate outer diameter could not be measured, and an accurate flat amount could not be obtained. Further, as is apparent from FIG. 7, when L> 1.5D, the flat tube flat amount is extremely small (that is, the flat ratio is extremely small) with respect to the flat tube flat amount. It is difficult to determine the flat amount of the straight pipe from the amount.

  Therefore, in order to perform measurement with as high accuracy as possible without being adversely affected by the connection portion, L is preferably about 0.5D to 1.5D, and particularly preferably about L = 0.5D. As described above, since the desired measurement unit distance 47 depends on the pipe coefficient, the flatness ratio for each pipe coefficient is obtained in advance for the particularly desirable measurement unit distance and is as large as possible without affecting the measurement of the flat amount. What is necessary is just to obtain | require the measurement part distance used as an aspect ratio.

  As described above, according to the embodiment of the present invention, even when the stress of the curved pipe connected to the straight pipe cannot be directly measured, the stress of the curved pipe can be accurately measured.

  The flat amount of the straight pipe can be easily measured from the outer diameter of the straight pipe. Further, by using the flatness ratio obtained in advance, the flattening amount of the curved pipe can be easily calculated from the flattening amount of the straight pipe. In addition, the straight pipe flatness measurement position is set to a position 0.5 to 1.5 times the diameter of the straight pipe from the straight pipe-curved pipe connection section to the straight pipe side. It is possible to accurately calculate the flat amount of the bent pipe without any problem.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, in order to calculate the stress of the bent pipe from the flat amount of the bent pipe, as described in JP-A-2003-344184, the moment is obtained and the stress is calculated from the moment. It can also be calculated. Further, without using the flatness ratio, it is possible to calculate the flattening amount and the stress directly generated in the curved pipe by the analysis by the finite element method or the like in the model shown in FIG. 6 from the flattening amount of the straight pipe.

The hardware block diagram which implement | achieves the stress evaluation apparatus 1 of a curved pipe. The flowchart which shows the evaluation process of the stress by the stress evaluation apparatus 1 of a curved pipe. The figure which shows the flat amount measuring method of the straight pipe | tube 35a. The figure which shows the flat amount measuring method of the straight pipe | tube 35a. The figure which shows the measuring method of flat amount. The figure which shows the test body for investigating the relationship between the flat amount measurement position of the straight pipe 53a, and the flat amount of a curved pipe. The figure which shows the relationship between the flat amount of a straight pipe and a curved pipe, and the analysis result by the distance from a curved pipe edge part. The figure which shows the stress measuring method of the conventional curved pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Stress evaluation apparatus 3 of a bending pipe ......... Analysis apparatus 5 ......... Flat measuring device 7 ......... Control part 9 ......... Storage part 11 ......... Media output part 13 ......... Communication control part 15 ......... Input unit 17 ......... Display unit 19 ......... Peripheral device I / F unit 21 ......... Bus 34 ......... Ground 35a, 35b ......... Straight pipe 37 ......... Bent pipe 39 ......... Buried pipe 41 ......... Flatness measuring part 43 ... ... Pipe connecting part 45 ... ... Pipe diameter 47 ... ... Measuring part distance 49 ... ... Pipe bodies 50, 50a, 50b ... ... Section 51 ... ... Pipe Top 52 ......... Pipe bottoms 53a and 53b ... Straight pipe 55 ... ... Curved pipe 57 ... ... Pipe connection part 59 ... ... Pipe diameter 61 ... ... Measuring part distance 63a, 63b ... ... Flange 65 ... …… Floor 67 ………… Stress measurement unit 69 ………… Analysis result 71 ……… Ground 73a, 73b ……… Straight pipe 75 ………… Bent pipe

Claims (3)

A method for evaluating stress of a curved pipe in a pipe body in which a straight pipe and a curved pipe are connected,
A step (a) of setting a flat amount measuring part at a position 0.5 to 1.5 times the diameter of the straight pipe from the connecting part between the straight pipe and the curved pipe to the straight pipe side;
A step (b) of measuring a flat tube flat amount in the flat amount measuring unit;
Calculating the flat amount of the curved pipe based on the flat amount of the straight pipe;
A step (d) of calculating a stress of the bent pipe based on a flattening amount of the bent pipe;
A stress evaluation method for a curved pipe, comprising: In accordance with the pipe coefficient of the tubular body, the flattening ratio between the flattening amount in the central cross section of the curved pipe and the flattening amount of the straight pipe in the flattening amount measuring unit is calculated in advance.
2. The method for evaluating stress in a curved pipe according to claim 1, wherein in the step (c), a flattening amount of the curved pipe is calculated from the flatness ratio. A stress evaluation device for a curved pipe in a pipe body in which a straight pipe and a curved pipe are connected,
Means for setting a flat amount measuring unit at a position 0.5 to 1.5 times the diameter of the straight pipe from the connecting part between the straight pipe and the curved pipe to the straight pipe side;
Means for measuring a flat amount of the straight pipe in the flat amount measuring unit;
Means for calculating the flattening amount of the curved pipe based on the flattening amount of the straight pipe;
Means for calculating a stress of the bent pipe based on a flattening amount of the bent pipe;
A stress evaluation apparatus for a curved pipe, comprising:

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